16.5 Commercial use of plant hormones

Question 1

what are commercial uses of auxin

Answer 1

• rooting powders (stimulates root growth in cuttings)
• inhibits fruit abscission (auxins sprayed to prevent fruits dropping to the ground and rotting)
• weed killers

Question 2

how are auxins used as weed killers

Answer 2

• high conc causes rapid growth (tissues, especially roots, become distorted and damage allows pathogens to enter)
• synthetic auxins are used in high conc
• useful in fields of cereals and on lawns (grasses are less sensitive to auxin so aren’t affected as much)
• weed killer selectively destroys broad-leaved weeds
• simple and cheap to produce, have low toxicity to mammals and are selective

Question 3

what are commercial uses of gibberellins

Answer 3

• treats unpollinated flowers (causes them to develop fruit and is useful in seedless fruits)

Question 4

what are parthenocarpic fruits

Answer 4

fruits that have been formed without fertilisation

Question 5

what are the commercial uses of ethene

Answer 5

• stimulates fruit ripening (useful in fruits that are liable to damage during transport)
• fruits are picked when unripe/hard, transported and then artificially ripened in transit or at destination using ethene
• ensures each batch ripens at the same rate and so are at the same stage when put out to be sold

Question 6

list general commercial uses of plant hormones

Answer 6

• rooting powder
• weedkiller
• prevent abscission of fruits
• ripening fruits
• seedless fruits
• control fruit drop
• restrict hedge growth

Question 7

why do cool conditions slow the rate of ripening even if ethene is present

Answer 7

• lower temp means ethene moves slower
• channel proteins work sower
• ethene takes longer to move through the plant
• enzymes/reactions work slower